Quadruped Walking Robot

ABSTRACT

The present invention provides a quadruped walking robot the production costs and weight of which can be reduced by reducing the number of driving portions, and which is capable of carrying out stabilized walking motions even with the degree of freedom reduced in the leg portions. 
     A quadruped walking robot  1  according to the present invention comprises: a horizontal swivel portion  4  disposed so as to freely swivel in the horizontal direction in the main body portion  2 ; a horizontal swivel driving portion  5  for driving and turning the horizontal swivel portion  4  in the horizontal direction; an upper side upper leg portion  9  rotatably axially attached in the horizontal swivel portion  4  so as to freely turn in the vertical direction; a lower side upper leg portion  11  disposed roughly parallel to the lower part of the upper side upper leg portion  9 ; an upper leg driving and turning portion  10  for driving and turning the upper side upper leg portion  9  in the vertical direction; a lower leg portion  13  in which the distal end part of the upper side upper leg portion  9  and the distal end part of the lower side upper leg portion  11  are axially supported vertically at the upper end portion; and a grounding portion  17  disposed at the lower end portion of the lower leg portion  13 ; and a resilient extension and contraction portion  12 , disposed at an intermediate portion of the lower side upper leg portion  11 , which resiliently extends and contracts in the lengthwise direction.

FIELD OF THE INVENTION

The present invention relates to a quadruped (four-legged) walking robothaving four leg sections and is self-moving by actuating the respectiveleg sections.

BACKGROUND OF THE INVENTION

Conventionally, various self-moving robots have been developed, some ofwhich have wheels, others of which have caterpillars, and still othersof which have leg sections. As a walking robot having leg sections,multi-legged walking robots such as a biped or two-legged robot, athree-legged robot, a quadruped or four-legged robot, a six-leggedrobot, etc., have been developed. In particular, various types ofquadruped walking robots have recently been developed in view of highstability in walking motions, and by a reason that these robots aremanufactured mimicking a four-legged animal such as, for example, a dog,a cat, etc.

A walking motion of the quadruped walking robot is carried out in such amanner that, for example, in a state where the tip ends of the threelegged sections are grounded to support the weight of a main bodyportion, etc., the remaining one leg is grounded after being moved toanother point of the ground using the leg as a free or idle leg, andwalking and movement are executed with the weight of a robot supported,by changing over such grounding legs and an idle leg at the respectiveleg sections by turns.

As such a quadruped walking robot, Patent Document 1 refers to amulti-legged walking robot in which a plurality of legs or leg sectionsare provided for the sides of the main body portion, and describes aconstruction in which the respective legs are provided with the firstturning axis, the second turning axis and the third turning axis. A legof the quadruped walking robot according to Patent Document 1 iscomposed of a first unit disposed at the side of the main body portion,a second unit attached to the first unit via a first joint portion, anda third unit attached to the second unit via a second joint portion,wherein the first joint portion is composed of a first turning axishaving its axial direction in the direction parallel to the side of themain body portion, and a second turning axis having its axial directionin the perpendicular direction to the side of the main body portion, andthe second joint portion is composed of a third turning axis parallel tothe second turning axis.

Patent Document 1: Japanese Published Unexamined Patent Application No.2002-11679

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, the above-described conventional multi-legged walking robot hasthe following problems.

(1) Since the first, the second and the third turning axes are turned ina multi-legged walking robot according to Patent Document 1, it isnecessary to provide a driving portion such as a motor to drive therespective turning axes, wherein twelve driving portions are totallyrequired in a case of four legs. Therefore, there is a problem that thenumber of driving portions is increased, the production costs thereofare remarkably raised, and the weight is incidentally increased.(2) Also, only by reducing the number of turning axes in order todecrease the number of driving portions, the degree of freedom of thelegs is reduced, wherein since it becomes impossible to move the tips ofthe legs to optional positions, stabilized walking control cannot becarried out, and in particular where ZMP control is executed to carryout stabilized walking, the tips of the ground legs cannot be moved tooptional positions. Therefore, there are other problems that the balanceof the robot is worsened, the tips of the legs slip on the ground duringwalking, and the walking is not stabilized.

The present invention has been made to solve the above-describedconventional problems, and an object thereof is to provide a quadrupedwalking robot capable of achieving a decrease in production costs andlightening the weight thereof by reducing the number of driving portionsand capable of carrying out stabilized walking motions even if thedegree of freedom in the leg sections is lowered.

Means for Solving the Problems

In order to solve the above-described problems, a quadruped walkingrobot according to the present invention includes the followingconstruction.

A quadruped walking robot according to a first aspect of the presentinvention has four leg sections at the sides of a main body portion,wherein the leg section includes a horizontal swivel portion disposed soas to freely swivel in the horizontal direction in the main bodyportion; a horizontal swivel driving portion disposed in the main bodyportion, which drives and turns the horizontal swivel portion in thehorizontal direction; an upper side upper leg portion rotatably axiallyattached to the horizontal swivel portion so as to freely turn in thevertical direction; a lower side upper leg portion disposed roughlyparallel to the lower part of the upper side upper leg portion, which isrotatably axially attached to the horizontal swivel portion so as tofreely turn in the vertical direction; an upper leg driving and turningportion disposed in the horizontal swivel portion, which drives andturns the upper side upper leg portion in the vertical direction; alower leg portion in which the distal end part of the upper side upperleg portion and the distal end part of the lower side upper leg portionare axially supported vertically at the upper end portion; and agrounding portion disposed at the lower end portion of the lower legportion; wherein the lower side upper leg portion is provided with aresilient extension and contraction portion that is disposed at anintermediate part thereof and is resiliently extended and contracted inthe lengthwise direction.

With such a construction, the following actions can be brought about.

(1) Since the upper side upper leg portion is driven and turned in theupward direction or the downward direction by driving the upper legdriving and turning portion of the leg portion, it is possible to makethe lower leg portion into an idle leg by moving the same in the upwarddirection and to ground it by moving the same in the downward direction.Also, by driving the horizontal swivel driving portion and moving thehorizontal swivel portion in the right direction or the left directionwhen the leg portion is an idle leg, it is possible to swivel the legportion in the forward direction or the backward direction.(2) By carrying out a crawl-walking motion in which a motion of makingthe lower leg portion of the leg portion into an idle leg by moving itupward, swiveling the leg portion in the forward direction and groundingthe same is executed one after another in the respective leg portions,it is possible to cause the quadruped walking robot to advance, retractand turn. At this time, the posture of the main body portion iscontrolled by a control unit, with the main body portion supported bythree leg portions other than the leg portion which is made into an idleleg, so that the ZMP (Zero Moment Point) which is a point on the groundon which the total sum of the gravities of the respective parts of thequadruped walking robot and the moments based on inertia forces are madeinto zero is positioned inside a triangle for which the grounding pointsof the grounding legs are made into vertices thereof, a so calledsupporting polygon. Accordingly, stabilized walking motions can becarried out.(3) By resiliently extending and contracting the resilient extension andcontraction portion, it is possible to vary the inclination of the lowerleg portion with respect to the upper side upper leg portion, whereinthe posture of the leg portions can be varied in association withmovement of the main body portion and the posture thereof at the time.Accordingly, even a dual-driving system that has two driving portionsper leg portion can bring about stabilized walking motions without thegrounding portion slipping on the ground.(4) Since the leg portion is composed of the dual-driving system thathas two driving portions per leg portion, it is possible to reduce thenumber of driving portions in comparison with a triple-driving system,wherein the production costs can be lowered, and at the same time, theweight can be lightened.(5) Although the leg portion is a dual-driving system including twodriving portions, it is possible to achieve a walking motion close to anormal triple-driving system and three degrees of freedom since thelower side upper leg portion includes a resilient extension andcontraction portion.

Herein, the quadruped walking robot is provided with four leg portions,each of which is located at both sides of the front part and the rearpart of the main body portion thereof. In a state where the groundingportions of the three leg portions thereof are grounded and support theweight of the main body portion, the remaining one leg portion is madeinto an idle leg and is moved to another point of the ground. Afterthat, the leg portion is grounded there. That is, it is possible toexecute a crawl walking motion in which walking is carried out byalternately changing over the grounding leg portions and the idle legfor all leg portions, and a trot walking motion in which walking iscarried out by making one pair of diagonal leg portions of the four legportions, for example, the leg portion at the right side portion of thefront part and the leg portion at the left side portion of the rear partinto idle legs, and making the remaining two legs into grounding legs,and alternately changing over the idle leg portions and the groundingleg portions. In addition, where a trot walking motion is carried out byproviding a locking mechanism portion so that the sliding portion of theresilient extension and contraction portion is locked at the tubularportion so as not to be extended and contracted, it is preferable thatthe resilient extension and contraction portion is locked by operatingthe locking mechanism portion.

A resilient extension and contraction portion that is provided with atubular portion disposed in the lengthwise direction of the lower sideupper leg portion, and a sliding portion slidably inserted into thetubular portion, and a spring member fitted inside the tubular portionmay be used.

A motor such as a geared motor may be used as the horizontal swiveldriving portion and the upper leg driving and turning portion. Also,turning axes fixed at the horizontal swivel portion and the upper sideupper leg portion are turned via one through a plurality of gears,whereby it is possible to drive and turn the horizontal swivel portionand the upper side upper leg portion.

A quadruped walking robot according to Claim 2 of the present inventionhas a construction in the invention of Claim 1, in which the resilientextension and contraction portion includes a tubular portion disposed inthe lengthwise direction of the lower side upper leg portion, a slidingportion slidably inserted into the tubular portion, and a spring memberfitted inside the tubular portion and pressing the sliding portion inthe extension and contraction direction.

With the construction, the following actions can be brought about inaddition to those of Claim 1.

(1) Since the sliding portion inserted into the tubular portion slidesalong the inner wall of the tubular portion, and at the same time, ispressed by a spring member fitted in the tubular portion, the resilientextension and contraction portion is resiliently extended andcontracted, wherein it is possible to vary the posture of the legportions corresponding to movement of the main body portion and theposture thereof at the time. Therefore stabilized walking can be carriedout.

A quadruped walking robot according to Claim 3 of the present inventionhas a construction in the invention of Claim 1 or Claim 2, in which alocking mechanism portion, disposed in the resilient extension andcontraction portion of the respective leg portions, for locking andunlocking the resilient extension and contraction portion is provided.

With the construction, the following actions can be brought about inaddition to those of Claim 1 or Claim 2.

(1) Since the resilient extension and contraction portion can be lockedor unlocked so as not to extend and contract by the locking mechanismportion, the resilient extension and contraction portion is resilientlyextended and contracted by unlocking the same where the quadrupedwalking robot carries out crawl walking, and a stabilized walking motioncan be carried out. For example, where a trot walking motion is carriedout, the resilient extension and contraction portion is locked to causethe lower leg portion not to be inclined toward the main body portiondue to movement of the main body portion, etc., wherein a stabilizedtrot walking motion can be carried out.

Herein, there are some locking mechanism portions, one of which isprovided with a locking hole drilled in the tubular portion and aninsertion pin inserted into the locking hole, wherein locking is carriedout by inserting the insertion pin into the locking hole, and the otherof which is provided with a solenoid, an insertion pin fixed at themovable portion of the solenoid, and a locking hole or a locking grooveformed in the resilient extension and contraction portion, into whichthe insertion pin is inserted, wherein locking is carried out by theinsertion pin being inserted into the locking hole or the locking grooveby supplying electricity to the solenoid.

A quadruped walking robot according to a fourth aspect of the presentinvention has a construction in the invention of the third aspect, inwhich the locking mechanism portion is provided with a locking holedrilled in the tubular portion and an insertion pin inserted into thelocking hole.

With the construction, the following actions can be brought about inaddition to those of Claim 3.

(1) By inserting the insertion pin into the locking hole, it is possibleto prevent the sliding portion from sliding inside the tubular portion,and by pulling out the insertion pin from the locking hole, it ispossible to unlock the sliding portion.

EFFECTS OF THE INVENTION

As described above, with the quadruped walking robot according to thepresent invention, the following advantageous effects can be broughtabout.

According to the invention of Claim 1,

(1) As for the leg portion, since a dual-driving system having twodriving portions per leg portion is employed, it is possible to providea leg walking robot capable of reducing the number of driving portionsin comparison with a triple-driving system, reducing the productioncosts and lightening the weight.(2) Since, by resiliently extending and contracting the resilientextension and contraction portion, the inclination of the lower legportion can be varied for the upper side upper leg portion, and theposture of the leg portions can be varied, corresponding to movement ofthe main body portion and the posture thereof at the time, a quadrupedwalking robot can be provided, which is excellent in stability and cancarry out stabilized walking motions without the grounding portionsliding on the ground even in the case of a dual-driving systemincluding two driving portions per leg portion.(3) Since the lower side upper leg portion includes a resilientextension and contraction portion although the leg portion is based on adual-driving system having two driving portions, it is possible toachieve a walking motion close to a normal triple-driving system ofthree degrees of freedom. Therefore, it is possible to provide aquadruped walking robot, which has excellent stability in walkingmotions, capable of smoothly walking.

According to the invention of Claim 2, in addition to the effect ofClaim 1,

(1) Since the sliding portion inserted into the tubular portion slidesalong the inner wall of the tubular portion, and at the same time, ispressed by a spring member fitted in the tubular portion, the resilientextension and contraction portion is resiliently extended andcontracted, wherein it is possible to vary the posture of the legportions corresponding to movement of the main body portion and theposture thereof at the time. Therefore, it is possible to provide aquadruped walking robot that is able to carry out stabilized walking andis excellent in stability.

According to the invention of Claim 3, in addition to the effects ofClaim 1 or Claim 2,

(1) Since it is possible to lock the resilient extension and contractionportion by the locking mechanism portion so as not to extend andcontract and to unlock the same, the resilient extension and contractionportion is resiliently extended and contracted by unlocking the same andstabilized walking motions can be carried out where the quadrupedwalking robot carries out a crawl walking motion, and, for example,where a trot walking motion is carried out, a stabilized trot walkingmotion can be executed by locking the resilient extension andcontraction portion so that the lower leg portions are not inclinedtoward the main body portion due to movement of the main body portion.That is, various types of walking movements are possible only byactuating or unlocking the locking mechanism portion, wherein it ispossible to provide a quadruped walking robot that is excellent indiversity of walking motions.

According to the invention of Claim 4, in addition to the effects ofClaim 3,

(1) It is possible to prevent the sliding portion from sliding insidethe tubular portion by inserting the insertion pin into the lockinghole, and it is possible to unlock the sliding portion by pulling outthe insertion pin from the locking hole. Accordingly, it is possible toprovide a quadruped walking robot in which switching of walking motionscan be simply carried out.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view depicting the major parts of the legportion of the front part of a quadruped walking robot according to afirst Embodiment;

FIG. 2 is a rear side view of a leg portion of the quadruped walkingrobot according to the first Embodiment;

FIG. 3A is a schematic view describing a crawl walking motion of aquadruped walking robot according to the first Embodiment; FIG. 3B is aschematic view describing a crawl walking motion of a quadruped walkingrobot according to the first Embodiment; FIG. 3C is a schematic viewdescribing a crawl walking motion of a quadruped walking robot accordingto the first Embodiment; FIG. 3D is a schematic view describing a crawlwalking motion of a quadruped walking robot according to the firstEmbodiment; and FIG. 3E is a schematic view describing a crawl walkingmotion of a quadruped walking robot according to the first Embodiment;

FIG. 4A is a schematic view describing ZMP control when a quadrupedwalking robot according to the first Embodiment makes a crawl walkingmotion; and FIG. 4B is a schematic view describing ZMP control when aquadruped walking robot according to the first Embodiment makes a crawlwalking motion;

FIG. 5A is a schematic view describing a motion of a resilient extensionand contraction portion of a quadruped walking robot according to thefirst Embodiment; and FIG. 5B is a schematic view describing a motion ofa resilient extension and contraction portion of a quadruped walkingrobot according to the first Embodiment;

FIG. 6 is a partially sectional side view of the major parts of alocking mechanism portion; and

FIG. 7 is a partially sectional side view of the major parts depictinganother example of the locking mechanism portion.

DESCRIPTION OF THE SYMBOLS

-   -   1 Quadruped walking robot    -   2 Main body portion    -   2 a Upper side main body plate    -   2 b Lower side main body plate    -   2 c Fixing hole    -   2 d Widened portion    -   20 a,3 b,3 c Leg portions    -   4 Horizontal swivel portion    -   4 a Upper side swivel plate    -   4 b Lower side swivel plate    -   4 c,4 d Side part swivel plates    -   4 e Fixing hole    -   5 Horizontal swivel driving portion    -   5 a Horizontal driving axis    -   6 Horizontal driving side gear    -   7 Horizontal driven side gear    -   8 Horizontal swivel axis    -   9 Upper side upper leg portion    -   9 a Upper side upper leg portion turning axis    -   9 b Upper leg driven side gear    -   10 Upper leg driving and turning portion    -   10 a Upper leg driving axis    -   10 b Upper leg driving side gear    -   11 Lower side upper leg portion    -   11 a Lower side upper leg turning axis    -   11 b Lower leg portion side member    -   11 c Horizontal swivel portion side member    -   12 Resilient extension and contraction portion    -   12 a Tubular portion    -   12 b Sliding portion    -   12 c Spring member    -   13 Lower leg portion    -   13 a, 13 b Lower leg plates    -   14 Upper side lower leg axis    -   15 Lower side lower leg axis    -   16 Shock-absorbing portion    -   17,17 a,17 b,17 c Grounding portions    -   18 a,18 b Supporting polygons    -   19 a,19 b ZMPs    -   20 a,20 b Setting ZMPs    -   21 Locking mechanism portion    -   22 Casing portion    -   23 Solenoid portion    -   24,28 Insertion pins    -   25,27 Locking holes    -   26 Locking groove

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, a description is given of one embodiment of the presentinvention with reference to FIG. 1 through FIG. 7.

First Embodiment

FIG. 1 is a perspective view depicting the major parts of the legportion of the front part of a quadruped walking robot according to thefirst Embodiment, and FIG. 2 is a rear side view of a leg portion of thequadruped walking robot according to the first Embodiment. Also,although a description is given of only one leg portion of the frontpart of the quadruped walking robot, the respective leg portions havethe same construction, and a description of the other leg portions isomitted.

In the drawing, reference numeral 1 denotes a quadruped walking robotaccording to the first Embodiment, and reference numeral 2 denotes amain body portion composed of an upper side main body plate 2 a and alower side main body plate 2 b vertically disposed parallel to eachother and having widened portions 2 d at the front end portion thereofand the rear end portion thereof. Reference numeral 20 a denotes leftand right leg portions at the front part of the quadruped walking robot1. Reference numeral 4 denotes a horizontal swivel portion provided atthe side of the widened portion 2 d of the main body portion 2 so as tofreely swivel in the horizontal direction. Reference numeral 5 denotes ahorizontal swivel driving portion, which is fitted and fixed in arectangular fixing hole 2 c drilled at the upper side main body plate 2a of the main body portion 2, for driving and swiveling the horizontalswivel portion 4. Reference numeral 6 denotes a horizontal driving sidegear fixed at the horizontal driving axis 5 a (Refer to FIG. 2) of thehorizontal swivel driving portion 5. Reference numeral 7 denotes ahorizontal driven side gear engaged with the horizontal driving sidegear 6, and reference numeral 8 denotes a horizontal swivel axis fixedat the horizontal driven side gear 7. The horizontal swivel portion 4 iscomposed of an upper swivel plate 4 a on the upper side, a lower sideswivel plate 4 b on the lower side, and side swivel plates 4 c and 4 dat both side portions. The horizontal swivel axis 8 has the upper endportion and the lower end portion fixed at the upper side swivel plate 4a and the lower side swivel plate 4 b, which are rotatably axiallysupported at the upper side main body plate 2 a of the main body portion2 and the lower side main body plate 2 b thereof.

Reference numeral 9 denotes an upper side upper leg portion rotatablyaxially supported at the horizontal swivel portion 4 in the verticaldirection at one end part thereof. Reference numeral 9 a denotes anupper side upper leg portion turning axis fixed at one end portion ofthe upper side upper leg portion 9 and rotatably axially supported atthe side portion swivel plates 4 c and 4 d. Reference numeral 10 denotesan upper leg turning and driving portion, which is fitted and fixed in arectangular fixing hole 4 e drilled in the side portion swivel plate 4c, for driving and turning the upper side upper leg portion 9. Referencenumeral 11 denotes a lower side upper leg portion disposed roughlyparallel to the lower part of the upper side upper leg portion 9 androtatably axially supported at the horizontal swivel portion 4 at oneend part thereof. Reference numeral 11 a denotes a lower side upper legturning axis fixed at one end portion of the lower side upper legportion 11 and rotatably axially supported at the side portion swivelplates 4 c and 4 d. Reference numeral 12 denotes a resilient extensionand contraction portion disposed at an intermediate portion of the lowerside upper leg portion 11. Reference numeral 12 a denotes a tubularportion disposed along the lengthwise direction of the lower side upperleg portion 11 and fixed at the lower leg portion side member 11 b, and12 b denotes a sliding portion fixed at the horizontal swivel portionside member 11 c of the lower side upper leg portion 11 and slidablyinserted into the tubular portion 12 a. Reference numeral 13 denotes alower leg portion whose upper part is axially supported at the upperside upper leg portion 9 and at the other end portion of the lower sideupper leg portion 11. Reference numerals 13 a and 13 b denote a frontside lower leg plate and a rear side lower leg plate of the lower legportion 13, respectively. Reference numeral 14 denotes an upper sidelower leg axis fixed at the other end portion of the upper side upperleg portion 9 and axially supported at the upper end portion of thelower leg portion 13. Reference numeral 15 denotes a lower side lowerleg axis fixed at the other end portion of the lower side upper legportion 11 and axially supported at the lower part of the upper sidelower leg axis 14 of the lower leg portion 13. Reference numeral 16denotes a shock-absorbing portion composed of a plurality of supportingpins provided at the lower end portion of the lower leg portion 13 alongthe lengthwise direction and spring members fitted to the respectivesupporting pins. Reference numeral 17 denotes a grounding portiondisposed at the lower part of the shock-absorbing portion 16, the lowerpart of which is formed to be curvature-shaped.

In FIG. 2, reference numeral 5 a denotes a driving axis of thehorizontal swivel driving portion 5, which is a horizontal driving axishaving a horizontal driving gear 6 fixed thereon, and 9 b denotes anupper leg driven side gear fixed on the upper side upper leg turningaxis 9 a. Reference numeral 10 a is an upper leg driving axis that is adriving axis of the upper leg turning and driving portion 10, and 10 bdenotes an upper leg driving side gear fixed at the upper leg drivingaxis 10 a and engaged with the upper leg driven side gear 9 b. Referencenumeral 12 c denotes a spring member fitted inside the tubular portion12 b, one end of which is fixed at the bottom portion of the tubularportion 12 a and the other end of which is fixed at the distal end ofthe sliding portion 12 b.

Herein, a geared motor may be used as the horizontal swivel drivingportion 5 and the upper leg driving and turning portion 10.

With respect to the quadruped walking robot 1 according to the firstEmbodiment constructed as described above, a description is given belowof the walking motions thereof with reference to FIGS. 1 and 2.

First, a description is given of basic motions of a leg portion, inwhich the leg portion 3 is made into an idle leg from a grounded state,is swiveled in the horizontal direction, and thereafter is grounded.

As depicted in FIGS. 1 and 2, in order to raise the lower leg portion 12upward from a state where the grounding portion 17 is grounded on theground and to make the leg portion 3 into an idle leg, the upper legdriving and turning portion 10 is driven to turn the upper leg drivingside gear 10 b in the direction of the arrow y in FIG. 2, and the upperleg driven side gear 9 b engaged with the upper leg driving side gear 10b is turned rightward of the arrow, wherein the upper side upper legportion 9 is turned upward. In line therewith, the lower leg portion 13moves upward. Also, since the lower side upper leg portion 11 is turnedupward in line with upward turning of the upper side upper leg portion9, the grounding portion 17 of the lower leg portion 13 is able to keepa downward-faced posture.

In order to swivel the leg portion 3 in the horizontal direction in astate where the leg portion 3 is made into an idle leg, the horizontaldriving side gear 6 is turned in the direction of the arrow β by drivingthe horizontal swivel driving portion 5, and the horizontal driven sidegear 7 engaged with the horizontal driving side gear 6 is turnedrightward when observed from upward. Then, the horizontal swivel portion4 is turned rightward. Accordingly, the leg portion 3 is swiveledforward.

When the leg portion 3 is swiveled to a predetermined position, theupper leg turning and driving portion 10 is driven to turn the upper legdriving side gear 10 b rightward (in the direction of the arrow x) inFIG. 2, and the upper leg driven side gear 9 b is turned leftward toturn the upper side upper leg portion 9 downward, wherein the legportion 13 is moved downward to ground the grounding portion 17.

In addition, in order to carryout a smooth walking motion, the movementof the lower leg portion 13 in the vertical direction and the swivelmotion of the leg portion 3 in the horizontal direction can besimultaneously carried out. At this time, the grounding portion 17depicts a roughly arc-shaped locus.

Next, a description is given of a crawl walking motion based on repeatedexecution of the basic motions of the leg portion, which has beendescribed above, with respect to the respective leg portionssequentially, with reference to FIG. 3.

FIG. 3A through 3E are schematic views describing a crawl walking motionof a quadruped walking robot according to Embodiment 1.

In FIG. 3, reference numeral 1 denotes a quadruped walking robot, FIG. 2denotes a main body portion, and FIG. 3, 3A, 3B, and 3C denote legportions. Reference numerals 17, 17 a, 17 b, and 17 c denote groundingportions of the tips of the respective leg portions 3, 3 a, 3 b, and 3c.

As depicted in FIG. 3A, the grounding portions 17, 17 a, 17 b, and 17 care grounded on the ground in a state where the quadruped walking robotis stopped.

As depicted in FIG. 3B, the lower leg portion 13 of the leg portion 3 ismoved upward, and simultaneously the leg portion 3 is swiveled in theforward direction. At this time, the leg portion 3 is an idle leg, andthe grounding portion 17 thereof is off the ground. Further, the legportions 3 a, 3 b and 3 c are grounding legs, and the grounding portions17 a, 17 b and 17 c thereof are grounded, wherein the main body portion2 is supported at three points. After the leg portion 3 is swiveled inthe forward direction, the lower leg portion 13 is moved downward toground the grounding portion 17.

Subsequently, as depicted in FIG. 3C through 3E, the other leg portions3 a, 3 b and 3 c are made into idle legs as in the above-described legportion 3, in the order of the leg portion 3 c (FIG. 3C), the legportion 3 a (FIG. 3D) and the leg portion 3 b (FIG. 3E). At this time,the other remaining three leg portions are made into grounding legs andsupport the main body portion 2. The leg portions 3 a, 3 b and 3 c thatare made into idle legs are swiveled forward, and are stepped forward inthe advancing direction by turns and grounded, whereby the quadrupedwalking robot 1 carries out a crawl walking motion.

In addition, in FIG. 3, a description is given of walking in the forwarddirection of the quadruped walking robot 1. However, by adequatelycontrolling the horizontal swivel direction of the leg portions 3, 3 a,3 b and 3 c and sequence by which the leg portions are made into idlelegs, the quadruped walking robot 1 can move rearward, turn, and stampits feet, etc.

Next, a description is given of ZMP control in crawl walking, withreference to FIG. 4.

FIGS. 4A and 4B are schematic views describing the ZMP control for acrawl walking motion of a quadruped walking robot according to the firstEmbodiment.

In FIG. 4, reference numeral 18 a denotes a supporting polygon which isa triangle in which the grounding portions 17 a, 17 b and 17 c on theground are the vertices. Reference numeral 18 b denotes a supportingpolygon which is a triangle in which the grounding portions 17, 17 a and17 b are the vertices. Reference numerals 19 a and 19 b denote ZMPs(Zero Moment Points) that are the points on the ground where the totalsum of the gravities of the respective parts of the quadruped walkingrobot 1 and the moments due to inertia becomes zero. Reference numerals20 a and 20 b denote setting ZMPs preset so that the ZMPs are locatedinside the supporting polygons 18 a and 18 b. The setting ZMPs 20 a and20 b are established inside the supporting polygons 18 a and 18 b, andat the same time are set at such a position where smooth walking can becarried out, for example, a position where a gravity does not greatlychange in the crawl walking motion.

As depicted in FIG. 4A, the leg portion 3 is an idle leg, and the legportions 3 a, 3 b and 3 c are the grounding legs. The grounding portions17 a, 17 b and 17 c are grounded and support the main body portion 2 atthree points. Since the ZMP 19 a in the state supported by the threepoints is made coincident with the setting ZMP 20 a set in advance, thequadruped walking robot 1 does not fall down.

As depicted in FIG. 4B, the leg portion 3 that was an idle leg isgrounded. Continuously, when the leg portion 3 c is made into an idleleg, the control unit (not shown) first calculates the ZMP 19 b when themain body portion is supported by the grounding portions 17, 17 a and 17b of the leg portions 3, 3 a and 3 b at three points. Herein, the ZMP 19a is calculated by a ZMP equation on the basis of the position andposture of the main body portion 2.

Next, the control unit drives the horizontal swivel driving portion 5and the upper leg driving and turning portion 10 of the respective legportions 3, 3 a and 3 b as the grounding legs, and controls the positionand posture of the main body portion 2. That is, the horizontal swiveldriving portion 5 of the respective leg portions 3, 3 a and 3 b isdriven, and the respective leg portions 3, 3 a and 3 b are swiveledbackward. At this time, since the grounding portions 17, 17 a and 17 bof the respective leg portions 3, 3 a and 3 b are grounded on theground, the main body portion 2 moves to the position of a roughlyforward position of the main body portion 2′ toward the forwarddirection by backward swivel of the respective leg portions 3, 3 a and 3b, and the leg portions 3, 3 a and 3 b move to the positions of the legportions 3′, 3 a′ and 3 b′. Further, it is possible to incline theposture of the main body portion 2 by driving the upper leg turning anddriving portion 10 of the leg portions 3, 3 a and 3 b.

As described above, the quadruped walking robot 1 carries out crawlwalking and moves forward while the control unit is controlling theposture of the main body portion 2 so that the ZMP 19 b of the quadrupedwalking robot 1 is made coincident with the setting ZMP 20 b set insidethe supporting polygon 18 b.

Also, as depicted in FIG. 4B, where the main body portion 2 movesroughly forward in a state where the grounding portions 17, 17 a and 17b of the leg portions 3, 3 a and 3 b are grounded, the main body portion2 is caused to smoothly move by the resilient extension and contractionportion 12 secured at the respective leg portions 3, 3 a and 3 b.Hereinafter, a description is given of motions of the resilientextension and contraction portion.

FIG. 5A and FIG. 5B are schematic views describing motions of theresilient extension and contraction portion of a quadruped walking robotaccording to the first Embodiment. Also, in the drawings, referencesymbol “A” and “B” are plan views and side views, respectively.

In FIG. 5, reference symbol L1 denotes a distance between the sideportion of the main body portion 2 and the grounding portion 17, and L2denotes a swivel radius of the leg portion 3 in the horizontaldirection.

As depicted in FIG. 5A, the grounding portion 17 of the leg portion 3 isgrounded diagonally forward left of the main body portion 2. In thisstate, when the main body portion 2 moves in the forward direction asdescribed in FIG. 4B, the leg portion 3′ becomes roughly orthogonal tothe side portion of the main body portion 2′ on the plane as depicted inFIG. 5B. Since the distance L1 between the side portion of the main bodyportion 2′ and the grounding portion 17 is roughly the same as thedistance in the before-forwarding state depicted in FIG. 5A, thedistance L1 is smaller than the swivel radius L2 of the leg portion 3.Therefore, the resilient extension and contraction portion 12 providedat the lower side upper leg portion 11 is caused to contract, whereinthe grounding portion 17 side of the lower leg portion 13 is enteredinto an inclined state toward the side portion of the main body portion2′.

Herein, the quadruped walking robot 1 according to the first Embodimenthas two degrees of freedom because it is of a dual-driving system havingtwo driving portions 5 and 10 for one leg portion 3. Therefore, althoughit is not possible to set the posture of the leg portion 3 in a groundedstate to an optional posture, it is possible to vary the posture of thelower leg portion 13 of the leg portion 3′, corresponding to movement ofthe main body portion 2′, by extending and contracting the resilientextension and contraction portion 12 as described above, wherein thequadruped walking robot 1 can carry out stable walking without thegrounding portion 17 slipping on the ground.

Further, differing from the crawl walking motion, it is possible tocarry out a trot walking motion, in which a pair of leg portions on adiagonal line of the leg portions 3, 3 a, 3 b, and 3 c, for example, theleg portions 3 and 3 c are made into a set, and the one set of legportions is made into idle legs while the other set of leg portions 3 aand 3 b are made into grounding legs, and sets of the idle legs and thegrounding legs are alternately changed over. The ZMP control forcarrying out a trot walking motion is the same as the crawl walkingmotion, excepting that a rectilinear band-like area connecting a set ofgrounded leg portions on a diagonal line together, for example, thegrounding portions 17 of the leg portions 3 and 3 c, is made into asupporting polygon, the setting ZMP is established inside thecorresponding supporting polygon, and the position and posture of themain body portion 2 is controlled so that a ZMP is set to accord withthe setting ZMP.

In addition, where a trot walking motion is carried out, in order tocarry out a stabilized walking motion, it is possible to fix extensionand contraction of the resilient extension and contraction portion 12 sothat the grounding portion 17 side of the lower leg portion 13 is notinclined toward the side portion of the main body portion 2′ due toextension and contraction of the resilient extension and contractionportion 12 by the locking mechanism portion. Hereinafter, a descriptionis given of the locking mechanism portion with reference to FIG. 6.

FIG. 6 is a partially sectional side view depicting the major parts ofthe locking mechanism portion.

In FIG. 6, reference numeral 11 denotes a lower side upper leg portion,12 denotes a resilient extension and contraction portion, 12 a denotes atubular portion, 12 b denotes a sliding portion, 12 c denotes a springmember, 21 denotes a locking mechanism portion, 22 denotes a casingportion disposed on the outer wall of the tubular portion 12 a, 23denotes a solenoid portion disposed inside the casing portion 22, 24denotes an insertion pin fixed at the movable part of the solenoidportion 23, 25 denotes a locking hole drilled in the tubular portion 12a, and 26 denotes a locking groove provided at a position communicatingwith the locking hole 25 with a predetermined extension and contractionlength of the sliding portion 12 b.

As depicted in FIG. 6, at the locking mechanism portion 21, the solenoidportion 23 causes the insertion pin 24 to be inserted into the lockinghole 25 and the locking groove 26 by supplying electricity, or causesthe inserted pin 24 to be pulled out. By the insertion pin 24 beinginserted into the locking hole 25 and the locking groove 26, the slidingportion 12 b is fixed with respect to the tubular portion 12 a, wherethe resilient extension and contraction portion 12 can be fixed so asnot to extend and contract.

Therefore, since the resilient extension and contraction portion 12secured at the lower side upper leg portion 11 is not extended andcontracted, there is no case where the lower leg portion 13 is inclinedtoward the main body portion 2 due to movement of the main body portion2. Since, in the ZMP control for a trot walking motion, the position andposture of the main body portion 2 are controlled in a state where themain body portion 2 is supported at two points by leg portions on adiagonal line, it is sufficient that one leg portion has two degrees offreedom, wherein no such trouble occurs as the grounding portion 17slips in a crawl walking motion. Therefore, since the lower leg portion13 can hold a roughly vertical posture without inclining by fixing theresilient extension and contraction portion 12 so as not to extend andcontract, stabilized trot walking can be carried out without swaying ofthe main body portion 2. Additionally, by pulling out the insertion pin24 from the locking hole 25 and the locking groove 26, the resilientextension and contraction portion 12 can be resiliently extended andcontracted by the spring member 12 c. Therefore, the control unit (notshown) controls the electric current flowing in the solenoid portion 23of the locking mechanism portion 21 and unlocks the resilient extensionand contraction portion 12 so as not to extend and contract, and it ispossible to carry out stabilized crawl walking as described above. Thus,when selecting crawl walking or trot walking, it is possible todetermine whether or not the resilient extension and contraction portion12 is extended and contracted in response to the walking motion.

Next, a description is given of another example of the locking mechanismportion with reference to FIG. 7.

FIG. 7 is a partially sectional side view depicting the major parts ofanother example of the locking mechanism portion.

In FIG. 7, reference numeral 21′ denotes a locking mechanism portion, 27denotes a locking hole drilled in the tubular wall of the tubularportion 12 a, and 28 denotes an insertion pin inserted into the lockinghole 27.

As depicted in FIG. 7, since the resilient extension and contractionportion 12 can be manually locked and unlocked so as not to extend andcontract by inserting the insertion pin 28 into the locking hole 27 orpulling out the same therefrom, the insertion pin 28 is pulled out fromthe locking hole 27 where crawl walking is carried out, and theinsertion pin 28 is inserted into the locking hole 27 where trot walkingis carried out, wherein it is possible to carry out stabilized walkingwhen causing the quadruped walking robot 1 to perform either walking.

Since the quadruped walking robot 1 according to the first Embodiment isconstructed as described above, it has the following actions.

(1) By driving the upper leg driving and turning portion 10 of the legportion 3, the upper leg driving side gear 10 b is turned, and the upperleg driven side gear 9 b engaged with the upper leg driving side gear 9a is turned, wherein the upper side upper leg portion 9 is turned andmoved in the upward direction or in the downward direction, and thelower leg portion 13 can be made into an idle leg by moving it in theupward direction, and can be grounded by moving the same in the downwarddirection. In addition, by driving the horizontal swivel driving portion5 when the leg portion 3 is made into an idle leg, the horizontaldriving side gear 6 is turned, and the horizontal driven side gear 7engaged with the horizontal driving side gear 6 is turned, wherein thehorizontal swivel portion 4 is turned and moved in the right directionor in the left direction, and it is possible to swivel the leg portion 3in the forward direction or in the backward direction.(2) It is possible to carry out a crawl walking motion in which motionsof making the lower leg portion 13 of the leg portion 3 into an idle legby moving the same upward, swiveling the leg portion 3 in the forwarddirection and grounding the same are executed in sequence with respectto the leg portions 3, 3 a, 3 b and 3 c, and it is possible to move thequadruped walking robot 1 forward, backward and swivel the same. At thistime, since the control unit controls the posture of the main bodyportion 2 so that the center of gravity of the quadruped walking robot 1is located inside a triangle the vertices of which are the groundingportions of the grounding legs while supporting the main body portion 2by means of the remaining three leg portions other than the leg portionwhich is an idle leg, stabilized walking motions can be carried out.(3) As the resilient extension and contraction portion 12 is caused toresiliently extend and contract by the sliding portion 12 b insertedinto the tubular portion 12 a sliding along the inner wall of thetubular portion 12 a, at the same time the sliding portion 12 b ispressed by the spring member 12 c fitted in the tubular portion 12 a.When carrying out crawl walking, it is possible to vary the inclinationof the lower leg portion 13 in connection to the upper side upper legportion 9 by extending and contracting the resilient extension andcontraction portion 12, and it is possible to vary the posture of theleg portion 3, corresponding to the posture of the main body portion 2.Therefore, stabilized walking can be carried out without the groundingportion 17 slipping on the ground.(4) The locking mechanism portion 21 locks the sliding portion 12 b withrespect to the tubular portion 12 a by the insertion pin 24 beinginserted into the locking hole 25 and the locking groove 26 by supplyingelectricity of the solenoid portion 23 and locks the resilient extensionand contraction portion 12 so as not to extend and contract. Since thelower leg portion 13 is not inclined toward the main body portion 2 dueto movement of the main body portion 2, it is possible to carry outstabilized trot walking without swaying even in a two-point supportedstate. Further, the control unit can lock and unlock the resilientextension and contraction portion 12 so as not to extend and contract bycontrolling the electric current flowing in the solenoid portion 23,wherein when trot walking is carried out, the resilient extension andcontraction portion 12 is locked, and when crawl walking is carried out,the resilient extension and contraction portion 12 is unlocked. That is,the resilient extension and contraction portion 12 can be switched inresponse to the mode of walking motions.

INDUSTRIAL APPLICABILITY

As described above, the present invention relates to a quadruped walkingrobot having four leg portions and self-moving by actuating therespective leg portions. In particular, according to the presentinvention, it is possible to provide a quadruped walking robot theproduction costs and weight of which can be reduced by reducing thenumber of driving portions, and which is capable of carrying outstabilized walking motions even with the degree of freedom reduced inthe leg portions.

1. A quadruped walking robot having four legs at the side portions ofthe main body portion, wherein the respective leg portions comprise: ahorizontal swivel portion disposed so as to freely swivel in thehorizontal direction in the main body portion; a horizontal swiveldriving portion disposed in the main body portion, which drives andturns the horizontal swivel portion in the horizontal direction; anupper side upper leg portion rotatably axially attached in thehorizontal swivel portion so as to freely turn in the verticaldirection; a lower side upper leg portion disposed roughly parallel tothe lower part of the upper side upper leg portion, which is rotatablyaxially attached in the horizontal swivel portion so as to turn in thevertical direction; an upper leg driving and turning portion disposed inthe horizontal swivel portion, which drives and turns the upper sideupper leg portion in the vertical direction; a lower leg portion inwhich the distal end part of the upper side upper leg portion and thedistal end part of the lower side upper leg portion are axiallysupported vertically at the upper end portion; and a grounding portiondisposed at the lower end portion of the lower leg portion; and whereinthe lower side upper leg portion is provided with a resilient extensionand contraction portion that is disposed at an intermediate part thereofand is resiliently extended and contracted in the lengthwise direction.2. The quadruped walking robot according to claim 1, wherein theresilient extension and contraction portion comprises: a tubular portiondisposed in the lengthwise direction of the lower side upper legportion; a sliding portion slidably inserted into the tubular portion;and a spring member fitted inside the tubular portion and pressing thesliding portion in the extension and contraction direction.
 3. Thequadruped walking robot according to claim 1, further comprising alocking mechanism portion, disposed in the resilient extension andcontraction portion of the respective leg portions, for locking andunlocking the resilient extension and contraction portion.
 4. Thequadruped walking robot according to claim 3, wherein the lockingmechanism portion comprises a locking hole drilled in the tubularportion and an insertion pin inserted into the locking hole.
 5. Thequadruped walking robot according to claim 2, further comprising alocking mechanism portion, disposed in the resilient extension andcontraction portion of the respective leg portions, for locking andunlocking the resilient extension and contraction portion.